Flail mower

ABSTRACT

A flail mower has cutting blades suspended by flail rods from a horizontal rotatable shaft. The center portion of each rod is curved through 90* to form a radial arm and a pivot arm at opposite ends of the rod. The pivot arm is a close sliding and rotational fit in an aperture in a lug on the shaft, the axis of the aperture being parallel to the axis of the shaft. The pivot arm is located in position by a detachable spring clip on the distal end of the pivot arm, so that the flail rod and blade can be removed from the shaft by detaching the clip and sliding the pivot arm end of the rod out of the aperture. The radial arm extends through an aperture in the cutting blade and is formed with an enlarged head which retains the blade on the arm when subjected to centrifugal force upon rotation of the shaft. The blade is slidable along the radial arm and then along the pivot arm for removal from the rod when the rod is removed from the shaft.

United States Patent Aldred 1 Feb. 29,1972

[54] FLAIL MOWER Edward John Aldred, Ipswich, England [73] Assignee:Ransomes Sims & Jeiieries Limited, Ipswich, Suffolk, England [22] Filed:Mar. 20, I970 [21] Appl.No.: 21,366

[72] Inventor:

3,465,507 9/1969 Fishaw ..56/294 Primary Examiner-Russell R. KinseyAssistant Examiner-J. A. Oliff Attorney-Ira Milton Jones [57] ABSTRACT Aflail mower has cutting blades suspended by flail rods from a horizontalrotatable shaft. The center portion of each rod is curved through 90 toform a radial arm and a pivot arm at opposite ends of the rod. The pivotarm is a close sliding and rotational fit in an aperture in a lug on theshaft, the axis of the aperture being parallel to the axis of the shaft.The pivot arm is located in position by a detachable spring clip on thedistal end of the pivot arm, so that the flail rod and blade can beremoved from the shaft by detaching the clip and sliding the pivot armend of the rod out of the aperture. The radial arm extends through anaperture in the cutting blade and is formed with an enlarged head whichretains the blade on the arm when subjected to centrifugal force uponrotation of the shaft. The blade is slidable along the radial arm andthen along the pivot arm for removal from the rod when the rod isremoved from the shaft.

9 Claims, 5 Drawing Figures Patented. Feb. 29, 1972 2 Sheets-Sheet 1INVENTOR I Edward aim Patented Feb. 29, 1972 3,645,076

2 Sheets-Sheet 2 l1, 40 i 40 4/ x 4 INVENTOR Edward JE/Zm Aldred BY In}.

A'r'rora Y FLAIL MOWER This invention relates to flail mowers, forcutting grass.

A flail mower has a cutting blade freely suspended from a horizontalshaft by a flail which usually comprises a chain or swing arm. The blademay comprise a separate component fitted on the flail, or an edge of theflail may be sharpened to form the blade. In operation the shaft isrotated at a sufficient speed so that the blade is held out radiallywith respect to the shaftby centrifugal force and cuts the grass byimpact. If the cutting blade should strike a rigid object such as astone, brick or even a mound of earth, the flail swings rearwards andinwards relative to the shaft so as to reduce the effective flaildiameter. The cutting blade can thus ride over the obstruction and thereis little risk of damage.

Flail mowers generally have a number of cutting blades each mounted on aseparate flail rod, the blades being spaced across the mower so as tocut a broad swath. The flail rods may be mounted independently on theshaft, or may be mounted on the shaft as a group. In previous knownconstructions having independently mounted flail rods the shaft andmechanism for mounting each rod are expensive to manufacture. n theother hand previous known constructions having the flail rods mounted onthe shaft as a group have the disadvantage that the labor cost forreplacing a blade are much higher than with independently mounted flailrods.

According tothe invention there is provided a flail mower having acutting blade suspended by a flail from a horizontal rotatable shaft,wherein the flail comprises a rod curved intermediate its ends to form aradial arm and a pivot arm substantially perpendicular to'the radialarm, the radial arm carrying the cutting blade and the pivot arm beingmounted in a transverse bore in a lug or flange on the shaft for angularmovement about an axis substantially parallel to the axis of the shaft,and locking means retaining the pivot arm in the bore, the pivot armbeing 1 removable from the bore upon release of the locking means. Thelocking means preferably comprises a spring clip detachably mounted onthe end of the pivot arm.

ln=theflail mower of the invention the means for mounting the flail rodon the shaft is simple and inexpensive to manufacture, and the flail canreadily be removed from the shaft for replacement of a cutting blade.

The cutting blade is preferably a separate component having an aperturethrough which the radial arm of the flail rod extendsas a sliding fit,the outer end of the radial arm being provided with a head which retainsthe blade on thelarm when subjected to centrifugal force upon rotationof the shaft, the cutting blade being slidable along the rod for removaltherefrom when the rod is removed from the shaft.

The shape ofthe blade may be generally hexagonal, square, oval ortriangular. The blade, however, preferably'comprises a circular discdeformed into a part-spherical shell and having a central aperture forpassage of the radial arm of the flail rod, the blade being arrangedwith its concave side facing radially outwards and the head on theradial arm being small enough to be inside; the swept diameter of theblade. Such a blade has the advantage that its cutting edge may beformed by grinding the periphery of the shell against a flat surface. Byhaving the cutting blade in disc form, a cutting surface parallel to theground is presented to the grass yet the disc is free to rotate aboutthe flail rod and can provide a continuing sharp edge to the grass.

The flail mower according to the invention may comprise a self-propelledor tractor-drawn machine adapted to be mounted ,on and driven by atractor. The mower of course preferably includes a number of flailsspaced apart along the flail shaft and arranged to cut a broad swath inthe grass being mown.

One construction of a flail mower according to the invention will now.be described, by way of example, with reference to the accompanyingdrawings, in which:

FIG. 1 is a view of the flail shaft assembly of the mower with theflails shown in their extended positions when subjected to centrifugalforce upon rotation of the shaft.

FIG. 2 is a view of part of the shaft assembly of FIG. 1, taken in thedirection of arrow A,

FIG. 3 is a cross-sectional view through the shaft assembly of FIG. 1.

FIG. 4 shows part of a shaft assembly. having the shaft and flail rodsof FIG. 1 but with cutting blades of a different coristruction, and

FIG. Sis a view of the shaft assembly of FIG. 4, taken in the directionof arrow B.

The flail mower of this construction comprises a wheeled carriageadapted to run along the ground, a flail shaftwhich extends horizontallyacross the mower and is rotatably mounted at its ends on the carriage,the flail shaft being provided with flails fitted with cutting blades,and a motor mounted on the carriage and drivably connected to the flailshaft. Only the flail shaft 10 with its bearings and drive pulley, theflails l1 and the cutting blades 12 are shown in full lines in FIG. 1,with part of the sidewalls i3 of the carriage shown in broken lines.

The flail shaft comprises a square section tube 15 (FIG. 3) and twocylindrical section stub shafts 16 secured one in each end of the tube.Each stub shaft 16 has a large diameter inner end 17 which is a closefit within and welded to the tube, and a smaller diameter portion 18which extends with clearance through an aperture in the adjacentsidewall 13 of the carriage andis rotatably mounted in a ball bearing 19supported in a housing bolted to the outer surface of the sidewall 13.The outer end of one of the stub shafts 16 is fitted with a pulley 21drivably connected by a belt (not shown) to the drive shaft of the motorfor rotation of the flail shaft.

The square section tube 15 is fitted with rectangular section pivotblocks 25, half of which are spaced along one of the flat faces of thetube and the other half spaced along the diametrically opposite flatfaceand approximately opposite the corresponding blocks on the firstface of the tube. The pivot blocks 25 are welded to the tube and projectoutwards beyond one edge of the associated face of the tube as shown inFIG. 3, the blocks on one face projecting outwards in the oppositedirection from the pivot blocks on the opposite face. The outerprojecting end of each pivot block 25 has a transverse bore 26, the axisof which is parallel to the axis of the flail shaft 10, the bores 26 alllying in a common plane passing through the axis of the shaft 10.

The flailsll are mounted one on each of the pivot blocks 25. Each flailcomprises a circular section steel rod 27 which is curved intermediateits ends to form a pivot arm 28 and a radial arm 29 arrangedapproximately at right angles to one another. The pivot arm 28 projectsthrough the bore 26 in the associated pivot block and is held inposition therein by a spring cotter hairpin clip 30. The clip issubstantially U- shaped, one leg 31 of the clip being straight andextending through a transverse aperture in the end of the pivot arm 28and .the other leg 32 of the clip having a concave portion which engagesas a snug fit around part of the wall of the pivot arm. One end 35 ofthe bore 26 in the pivot block is flared outwards with a curvaturecorresponding to that of the curved portion of the flail rod 27, and theflail rod is arranged so that the curved portion engages along the wallof the flared end of the bore and the spring clip 30 is spaced close tothe opposite end of the pivot block 25. There is thus little free axialmove ment of the pivot arm 28 within the'bore 26, but the flail rod isnevertheless free to pivot about the axis of the bore.

The radial arm 29 of each flail rod extends through a central aperturein the associated cutting blade 12 and the outer end of the radial arm29 is enlarged to form a head 36 which retains the blade .12 on the arm.The blade 12 is formed from a circular disc of sheet steel deformed intoa shallow part-spherical shell, the periphery of the shell being roughground on a flat surface to form a cutting edge 37 on the shell. Theaperture for passage of the radial arm 29 is formed in the center of theshell, and the blade is mounted on the radial arm with the concave sideof the shell facing radially outwards from the flail shaft. The: head 36is of a size such that it is located wholly within the concave interiorof the blade 12 when the blade is engaged against the head.

The flails mounted on the pivot blocks 25 on one face of the tube 15 arearranged so that their pivot arms 28 extend into the left hand end ofthe bores in their pivot blocks, and the flails mounted on the pivotblocks 25 on the opposite face of the tube 15 are arranged so that theirpivot arms extend into the right-hand end of the bores in their pivotblocks. The radial arms 29 and the blades 15 are thus offset relative toone another along the length of the tube 15.

In operation, upon rotation of the shaft the blades 12 are forcedoutwards by centrifugal force against the heads 36 on the ends of theradial arms 29. The radial arms are thus maintained in a radial positionrelative to the shaft 10, and the blades 12 are of a size such that theycooperate to cut a broad swath in the grass being mown. If the bladestrikes a solid object, the flail rod 27 pivots rearwards relative tothe rotational direction of the shaft about the axis of the bore 26 inits pivot block, thereby decreasing the radial distance of the blade 12from the axis of the shaft 10. The centrifugal force holds the blade 12centered on the flail rod 27 so that the circular cutting edge 37 on theperiphery of the blade is substantially parallel to the ground uponpassage of the blade below the shaft. Moreover rotation of the blade 12around the radial arm 29 of the flail rod will cause different parts ofthe cutting edge to engage the grass in successive revolutions of theflail shaft.

Since the flails and cutting blades on one face of the square sectiontube are offset from their respective pivot blocks in the oppositedirection from the offset of the flails and blades relative to theirpivot blocks on the opposite face of the tube 15, the moments of forceproduced on the flail shaft by the cutting blades and flails whenrotating substantially balance out one another.

A flail rod 27 together with its blade 12 can readily be removed fromthe flail shaft by manually withdrawing the clip 30 from the rod 27 andthen withdrawing the rod from the bore 26 in the pivot block. The blade12 can then be removed from the flail rod 27 by sliding it down theradial arm 29, around the curved portion of the rod, and off the end ofthe pivot arm 28.

The length of the radial arm 29 and the shape and size of the blade 12is so selected in relation tothe position of the bore 26 in the pivotblock as to obtain the maximum reduction in operative diameter when theflail swings back to its radially innermost position upon striking anobject. In this position the radial arm 29 lies adjacent andapproximately parallel to one flat face of the square section tube 15and the back of the blade 12 abuts against the adjacent flat face of thetube, as shown in broken lines in FIG. 3.

The arrangement shown in FIGS. 4 and 5 has cutting blades and heads 41on the flail rods ofa different construction to those shown in FIGS.1-3. The other components of the two arrangements are however identicaland are denoted on the drawings by the same reference numerals.

Each cutting blade 40 shown in FIGS. 4 & 5 consists of a rectangularplate of sheet steel folded transversely into the shape of a V, the apexof the V-shaped blade having an aperture for passage of the radial arm29. The head 41 on the radial arm comprises a crossbar weldedtransversely across the end of the radial arm and arranged normal to theaxis of the shaft 10. When the blade 40 is forced outwards bycentrifugal force, the transverse fold in the blade lies along thecrossbar on the radial arm. The side edges 43 and ends 44 of the blade40 are bevelled to form cutting edges.

I claim:

I. A flail mower comprising a horizontally extending rotatable shafthaving thereon intermediate its ends a lug with a transverse boresubstantially parallel to the axis of the shaft, a flail mounted on saidlug and comprising a rod curved intermediate its ends to form inner andouter end portions substantially perpendicular to one another. the innerend portion of said rod forming a pivot arm which is mounted in the lugbore for free angular movement about an axis substantially parallel tothat of t e shaft, a cutting blade supported on the outer end portion ofsaid rod, and releasable locking means retaining the pivot arm in saidtransverse bore, whereby the pivot arm can be removed from the lug uponrelease of the locking means to provide for disconnection of the flailfrom the shaft.

2. A flail mower as claimed in claim 1, wherein the pivot arm projectsthrough the bore and the locking means are detachably mounted on saidprojecting end of the pivot arm.

3. A flail mower as claimed in claim 2, wherein the locking meanscomprises a spring clip detachably mounted on the end of the pivot arm.

4. A flail mower as claimed in claim 2, wherein one end portion of thebore in the lug is flared outwards, part of the curved portion of theflail rod is a close fit against the wall of said one end portion of thebore, and the locking means on the rod abut against the lug at the otherend of the bore, so that the pivot arm of the flail has little freeaxial movement in the transverse bore.

5. A flail mower as claimed in claim 1 wherein the cutting blade isformed with an aperture to slidably receive the rod, and the outer endportion of the rod is provided with a head which retains the bladethereon when subjected to centrifugal force upon rotation of the shaft,the cutting blade being slidable along the rod for removal therefromwhen the pivot arm is withdrawn from the bore in the lug on the shaft.

6. A flail mower as claimed in claim 5, wherein the cutting bladecomprises a disc deformed to provide a concave recess and having an edgethereof sharpened to form the cutting edge, the aperture for the rodbeing formed in the center of the concave portion of the blade, theblade being arranged so that its concave side faces radially outwards,and the recess being sufflciently large so that the head on the rod isinside the swept diameter of the blade.

7. A flail mower as claimed in claim 6, wherein the blade comprises acircular disc deformed into a part-spherical shell.

8. A flail mower as claimed in claim 5, wherein the cutting bladecomprises a metal plate deformed into the shape of a V and having acentral aperture in the apex of the V for passage of the flail rod, thehead on the rod comprising a crossbar welded to the end ofthe outer endportion.

9. A flail mower as claimed in claim 1 and including a plurality of saidflails arranged in two sets and carried by lugs mounted on diametricallyopposite sides of the shaft, the flails of one set having their pivotarms extending through the bores in their associated lugs in a directiontowards one end of the shaft, and the flails of the other set havingtheir pivot arms extending in the opposite direction through the boresof their associated lugs, whereby during rotation of the shaft the m0-ments of force produced on the shaft by one set of flails is at leastpartially balanced by the moments of force produced by the other set offlails.

tnun: AAA!

1. A flail mower comprising a horizontally extending rotatable shafthaving thereon intermediate its ends a lug with a transverse boresubstantially parallel to the axis of the shaft, a flail mounted on saidlug and comprising a rod curved intermediate its ends to form inner andouter end portions substantially perpendicular to one another, the innerend portion of said rod forming a pivot arm which is mounted in the lugbore for free angular movement about an axis substantially parallel tothat of the shaft, a cutting blade supported on the outer end portion ofsaid rod, and releasable locking means retaining the pivot arm in saidtransverse bore, whereby the pivot arm can be removed from the lug uponrelease of the locking means to provide for disconnection of the flailfrom the shaft.
 2. A flail mower as claimed in claim 1, wherein thepivot arm projects through the bore and the locking means are detachablymounted on said projecting end of the pivot arm.
 3. A flail mower asclaimed in claim 2, wherein the locking means comprises a spring clipdetachably mounted on the end of the pivot arm.
 4. A flail mower asclaimed in claim 2, wherein one end portion of the bore in the lug isflared outwards, part of the curved portion of the flail rod is a closefit against the wall of said one end portion of the bore, and thelocking means on the rod abut against the lug at the other end of thebore, so that the pivot arm of the flail has little free axial movementin the transverse bore.
 5. A flail mower as claimed in claim 1 whereinthe cutting blade is formed with an aperture to slidably receive therod, and the outer end portion of the rod is provided with a head whichretains the blade thereon when subjected to centrifugal force uponrotation of the shaft, the cutting blade being slidable along the rodfor removal therefrom when the pivot arm is withdrawn from the bore inthe lug on the shaft.
 6. A flail mower as claimed in claim 5, whereinthe cutting blade comprises a disc deformed to provide a concave recessand having an edge thereof sharpened to form the cutting edge, theaperture for the rod being formed in the center of the concave portionof the blade, the blade being arranged so that its concave side facesradially outwards, and the recess being sufficiently large so that thehead on the rod is inside the swept diameter of the blade.
 7. A flailmower as claimed in claim 6, wherein the blade comprises a circular discdeformed into a part-spherical shell.
 8. A flail mower as claimed inclaim 5, wherein the cutting blade comprises a metal plate deformed intothe shape of a V and having a central aperture in the apex of the V forpassage of the flail rod, the head on the rod comprising a crossbarwelded to the end of the outer end portion.
 9. A flail mower as claimedin claim 1 and including a plurality of said flails arranged in two setsand carried by lugs mounted on diametrically opposite sides of theshaft, the flails of one set having their pivot arms extending throughthe bores in their associated lugs in a direction towards one end of theshaft, and the flails of the other set having their pivot arms extendingin the opposite direction through the bores of their associated lugs,whereby during rotation of the shaft the moments of force produced onthe shaft by one set of flails is at least partially balanced by themoments of force produced by the other set of flails.